FIGS. 1 and 2 depict a prior art optical device having a lens 102, a nosepiece 104, a weighted counterbalance 106, and a supporting bar 108. Supporting bar 108 interconnects nosepiece 106 between lens 102 and counterbalance 108. The entire device is designed to be supported and balanced on the bridge of the wearer's nose. To achieve this affect, at least one of the lens, the nosepiece, and the counterbalance is adjustably displaceable about the supporting bar for maintaining balance.
The counterbalance, as shown in FIGS. 1 and 2 is preferably positioned below the position of the lens at the opposite side. As with the lens, the counterbalance is preferably adjustable longitudinally along the supporting bar. Rotational adjustment may not be readily needed, but is certainly a possibility.
Supporting bar 108 is generally a laterally extending, elongated bar for supporting the other elements. In a single lens configuration, the lens is mounted near or at one end, and the counterbalance is mounted near or at the other end. Therebetween is the nosepiece. Prior art supporting bars were generally uniform in cross-section throughout the portion on which the lenses, counterbalance, and or nosepiece could slide, and had linear tangential, longitudinal surfaces. The supporting bar would, for example, have a circular cross-section throughout, such as a cylindrical rod. D-shaped cross-sectional bars were also used with the flat surface preferably facing the wearer and engaging internal springs or other securing devices in the nosepiece, lens or counterbalance.
The nosepiece is generally disposed midway between the lens and the counterbalance. This, however, need not always be the case. With heavier counterbalances, shorter distances can be achieved on the counterbalance side of the supporting wire. The appropriate weighting of the nosepiece, itself, can provide sufficient weight to act as the counterbalance.